Multiplex electric thermometer.



' Patented July 22, 1902.

A. zELENY. MULTIPLEX `ELECTRI THERMOMETER.

lApplication filed Jan. 20, 1902.)

3 Sheets-Sheet 2.

(No Moden.)

Patented July 22, |902.

4 No. 705:,la7.

A. zELENY. vMULTIPLEX ELECTRIC THERMOMETER.

.Application med Jan. 2o, 1902.

3 Sheets-Sheet 3.

(No Model.)

mi if Q* TH: Noam s PETERS co, PHOTO-LMAO. wAsr-nn'cron, o4 c,

UNITED STATESk ANTHONY ZELENY, OFv MINNEAPOLIS, TO O.-E. THAYER, OF MIPATENT Orrrou.

MINNESOTA, ASSIGNOR OF ONE-HALF NNEAPOLIS, MINNESOTA.

M ULTIPLEAX ELECTRIC THERMOMETER.

SPECIFICATION forming part of Letters Patent No. 705,187, dated July 22,1902. Application filed January 20,1902. Serial No. 90,402." (No model.)

To @ZZ whom it may concern,.-

Be it known that I, ANTHONY ZELENY, a citizen of the United States,residing at Minneapolis, in the county of Hennepin and State ofMinnesota, have invented certain new and useful Improvements inMultiplex Electric Thermometers; and I do herebydeclare the following tobe a full, clear, and exact description of the invention, such as willenable others skilled in the art to which it appertains to make and usethe same.

My invention has for its object to provide improved means for readilydetermining at a reading-station the temperature at various distantpoints; and to this end it consists `of the noveldevices andcombinations of devices hereinafter described, and defined in theclaims.

My improved device for accomplishing the above result may very properlybe designated as a multiplex electric thermometer. It involves the useof a plurality of thermo-electric circuits or couples having individualthermo-electric junctions and a common thermoelectric junction. Thecommon thermo-electric j unction-ispreferably located at or in theimmediate vicinity of the reading-station, and as its temperature iseither known or capable of beingreadily determined it may be designatedas the known-temperature junction. The individual junctions are locatedat various distant points, and as their temperaturesare to be determinedby the use of the instru-- ment they may be properly designated as theunknown-temperature junctions.

A galvanometer or reading instrument is connected in oneof the leads tothe common or known-temperature junction, and a switch is also providedwhereby any thermo-electric circuit or couple may be closed into circuitwiththe common'thermo-electric j unction and common galvanometer.Otherwise stated,by means oi the switch the common or knowntemperaturejunction may be balanced against or made to react against any one of theindividual or unknown-temperature junctions, and the galvanox-neter willindicate the temperature at such unknown-temperature oru distantjunction. The system involves other novel and important features ofconstruction,

. This improved multiplex electric thermometer is capable of a very widerange of different uses; but in the drawings it is illustrated asapplied for determining temperature at 55 different levels in a seriesof storage-bins, such as are used in grain-elevators.

In the drawings like characters ind icate like parts throughout theseveral views.

Figure l is a view principally in diagram, 6o but with some parts shownin vertical section, illustrating my improved device applied asaboveindicated. Fig. 2 is a detail view in plan, showing the switch andswitchboard on an enlarged scale.- Fig. 3 is a vertical section 65outhe'line 3 3 of Fig. 2. Fig. 4 is a vertical section showing in detaila portion of one of the incasing tubes for the so-called individual orunknown-temperature junctions. Fig.

5 isa view corresponding to Fig. 4, but illus- 7o tratingaslightly-modified construction of the said tube. Figs. 6 and 7 are alsodetail views in vertical section, illustrating modified constructions ofthe incasing tubes and of the thermo-electric junctions supportedthereby. 7 5 The numeral l indicates grain-storage bins.

. The numeral 2 indicates a switchboard having contact-pins 3. Aswitch-lever 4, pivoted to said switchboard 2, is provided at its freeend with a sliding contact-head 5, which 8o coperates with thecontact-pins 3 and, as shown, is adapted tobe frictionally held in itsset position by a spring-pressed pin 6. (Best shown in Fig. 3.)

The numeral 7 indicates a suitable galva- 85 nometer or other readinginstrument which is sensitive to current-flow.

The numeral 8 indicates the common thern10-electric junction, and thenumeral 9 indicates the individual thermo electric j unc- 9o tions, theformer of which is located at the reading-station or in the vicinity ofthe galvanometer and switch and the latterof which are distributed atdifferent points within the bins l. In the illustration given thesether- 9 5 ino-electricj unctions 8 and 9 are formed of copper andGerman-silver wires twisted and soldered together. Theommon orknown-temlerature thermo electric junction S is arra`n`ged to reactagainst orfact in opposition to roo any of the individual orunknown-temperaall of which will hereinafter appear.

ture junctions 9 with which it is coupled.

This will be apparent by noting that the copper wires 10 and 10l areindicated by full lines, while the German-silver wires 11, 11a, andlllareindicated bydottedlines. Thesaid wires 10 extend one from eachjunction 9 to a different pin 3 of the switchboard 2. The slidingcontact-head 5 is connected to the copper member of the common junction8 by the wire 10a, and the galvanometer 7 is shown as interposed betweenthe sections of said wire 10i. The German-silver member of said commonjunction 8 is connected to the Germansilver member of all of theindividual or unknown-temperature junctions 9 by the common German-silver return-wire 11, having branches 11n.

The numeral 12 indicates a resistance-coil afforded by what is known asa low-temperature-coefcient coil or wirethat is, a coil or body of wirewhose resistance remains approximately constant under varyingtemperatures. The coil 12 is shown as interposed between sections of thereturn-wire 11, in the vicinity of the common junction 8,and itsconnections therewith areindicatedat 12a. These connections 12a to soineextent constitute thermo-electric junctions, and to prevent the samefrom interfering with the proper actions between the junctions 8 and 9it is essential that they be kept at the same temperature, and henceequally balanced. For this reason the said coil 12 is preferably placedwithin a tight box or inclosing compartment 13. The thermo-electricjunction 8 is also shown as placed within a box or closed compartment14, into which also the lower or bulb end of an ordinary thermometer 15is placed.

The numeral 16 indicates a thermo-electric junction of the samecharacter as those described, but which is located at a distant pointfrom the reading-station and is adapted to be used for testingpurposes-that is, for testing the accuracy of the system. The German-silver member of this junction 1G is shown as connected to thereturn-wire 11 by a German-silver wire 111'. The vcopper member of saidjunction 1G is connected to a pin onthe switchboard 2 by a copper wire10b. The said junction 1b is also preferably' inclosed in a tight box17, into which also the bulb or lower end of an ordinary thermometer 18is placed. This testing-junction 16 and its connections are not anessential feature of my invention.

To protect thewires and the junctions 9 from the grain or other materialwith which the bins will be filled, they are preferably placed withinmetal pipes or tubes, as shown at 19 in Fig. 4. These tubes or pipes 19will be properly supported within the bins, preferably from the overheadbin-supports. (Not shown.) To confine the air surrounding the junctions9 and prevent the circulation thereof upward through the pipe 19, plugs2O are shown as placed within the said pipes.

In the construction illustrated in Fig. 5 the pipe 19 is provided withlaterally-projecting thimbles 21, in which the junctions 9 are inclosed.The outer ends of the said thimbles 21 are shown as closed by caps 22,while their inner ends are shown as closed by plugs 23. The constructionillustrated in Fig. 6 is substantially the same as that illustrated inFig. 4, the only difference being that the wires 10 and 11L are directlyconnected to form the junctions 9.

The construction illustrated in Fig. 7 involves the pipe 19 withprojecting thimbles 21; but in this construction the thermo-electricjunctions 9 project through and depend from said thimbles 21, so thatthey may come in direct contact with the grain or other materials storedin the bins. These depending junctions 9 and their leads are of courseinsulated from the pipe 19 and thiinbles 2l. As shown, insulating-clamps24, applied to said thimbles 21, hold the leads of the said junctions.Instead of the metal pipes 19 hollow exible cables, of wire or othersuitable material, may be used. It will also be understood that thewires or leads 10 and 11 where they extend between the incasing tubes 19and the switchboard 2 may be protected in any suitable Way-as, forinstance, by being formed into a covered cable. It will be noted that bythe use of the switchboard and switch illustrated a very large number ofdistant individual or unknown-temperature junctions may be coupled intocircuit with the common junction 8. In the drawings only six of theseindividual junctions 9 are shown, and hence but six of theswitchboard-pins 3 are used in connection therewith.

The operation of the device described will be substantially as follows:For one illustration we will assume that the common junction 8 is keptat the constant temperature of melting ice-'to wit, 32 Fahrenheit. Nowit is evident that if the temperature of the particular individualjunction 9 which is coupled into circuit with the said common junction 8is also at the temperature of melting ice there will be no current-flowthrough the closed thermo-electric circuit or couple, for

the reason that the two thermo-electric junctions 8 and 9 are balancedagainst each other. If, however, the temperature of the two junctionsthus closed into circuit are different, there will be a iiow in the onedirection or the other through the closed thermo-electric circuit orcouple, and this flow will be indicated by the galvanometer. So far asmy present invention is concerned the galvanometer may be made to readeither in degrees directly or in volts or amperes, which are capable ofbeing translated into degrees. However, it is my intention to use inconnection with this system a galvanometer of the general character setforth and claimed in a companion application filed by me of even dateherewith, entitled Galvanometer. By the use of my improved galvanometerthe IOC) lor;

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temperature of a distant individual junction 9 may be directly read evenwhere the temperature of the common or known junction S is permitted tovary. The resistance or lowtemperature-coefticient coil l2 makesnegligible errors in readings due to different lengths of variouscircuits vand to change of resistance in the Wires of thel system due tovaryingtemperatures. Furthermore,the said coil serves to reduce toconvenient length the divisions on the scale.

It will of course be understood that any suitable combination of metalwires or leads may be used to form the thermo-electric j unctions. Forinstance, iron and copper might be used in some cases.

As already indicated, the device is capable of a very wide range of use.It is of course especially serviceable for indicating the te mperaturesat various inaccessible points, such as within bodies or piles of graincontained in bins or coal contained in the bunkers of vessels or instorage.

The device is also very serviceable for indicating the temperature atvarious distant points, which while accessible can be much moreconveniently read from a common point or station, such as thetemperatures 'in the various parts of cold-storage plants.

The device is of course capable of a large range of modification as todetails of construction and arrangement of parts within the scope of myinvention as herein claimed. It will of course be understood thatvarious other combinations of metals may be used for the thermo-electricjunctions and wires of the couples or thermo-electric circuits.

The expression galvanometer7 is herein used in a very broad sense toinclude any measuring instrument which is sensitive to an. electriccurrent or to a difference of potential.

The expression switch is herein used in a broad sense to cover alldevices capable of use to open and close the various circuits.

What I claim, and desire to secure by Letters Patent ot' the UnitedStates, is as follows:

i l. The combination with a galvanometer and a switch, of a plurality ofthermo-electric circuits having individual thermo electric junctions-anda common thermo-electric j unction, which common junction, by said`switch, may be connected withany fopposingt-individual junction, tocomplete the thermo-electric circuit, substantially as described.

2. The combination with a plurality of thermo-electric couples having acommon lead of a dierent metal than that of the individual leads, of acommon galvanometer and a switch for closing any couple into circuitwith said galvanometer, substantially as described.

3. The combination witha switch and a galvanometer, of a plurality ofthermo-electric circuits having individua] thermo -electric junctionsand a common thermo-electric j unction, which common junction is in oneof the leads to said galvanometer and, by said switch, is adapted to beconnected with any opposing individual junction, to complete thethermo-electric circuit, substantially as described.

4. The combination with a galvanometer and a switch, of a plurality ofthermo-electric circuits having a common return-lead and provided withindividualnthermo electric junctions anda common thermo-electric junction, which common junction, by said switch, may be connected withany opposing individual junction, to complete the thermo-electriccircuit, substantially as described.

5. The combination with a galvanometer and a switch, of a plurality ofthermo-electric circuits having individual thermo-electric junctions, acommon thermo-electric junction, and a resistance coil or device inoneof the leads to said commonj unction, which common junction, by saidswitch, may be connected with any opposing individual j unction, tocomplete the thermo-electric circuit, substantially as described.

6. The combination with a galvanometer and a switch, of a plurality ofthermo-electric circuits of different length and resistance, havingindividual thermo-electric junctions, a common thermo-electric j unctionand a common low-temperature-coeficient resistancewire, which common junction, byA said switch,

Vmay be connected with any opposing individual junction, to complete thethermo-electric circuit, substantially as described.

'7. The combination with a plurality of therino-electric circuits and aswitch, of a common branch of high resistance including a galvanometer,which common branch, by lsaid switch, is capable of being connected intoany one of the thermo-electric circuits, whereby said circuits, whensuccessively closed, have practically equal resistance enabling equaldifferences in temperature to produce, in the said various circuits,equal deiiections on the common galvanometer, substantially asdescribed. V

In testimony' whereof I affix my signature in presence of two witnesses.

ANTHONY ZELENY. wWitnesses:

` ELIZABETH KELIHER,

F. D. MERCHANT.

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